The present invention is related to one-sided foils, particularly, for use in capacitors and improved methods of making one-sided foils. Even more specifically, the present invention is directed to capacitors made from one-sided capacitor foils.
Miniaturization is an ongoing desire in the electronics industry. This desire is driven by consumer demands for smaller, more functional, devices with decreased size and weight. This demand is contrary to the demand for decreased cost. A common direction for capacitors in the industry is miniaturization. Many development efforts have focused on miniaturization and one aspect of this development is referred to in the art as embedded capacitance as represented in U.S. Pat. No. 7,745,281 which is incorporated herein by reference. It is common in the art to use a high surface area foil in order to provide increased capacitance. Methods of forming this high surface area include etching or deposition methods.
With embedded technology it is desirable to only have high surface area on one side of the foil. Having the high surface area surface on only one side maximizes the capacitance and reduces the thickness of the device simultaneously. This also allows for treating the non-high surface area side in such a way as to prepare it for use in the embedded application, including providing a surface that is better suited for electrical connection.
Additive processes can achieve this one sided structure. However, additive technologies require excessive cost in order to manufacture one-sided foils. The commercially available capacitor foils are still preferably formed by electrochemical etching. Electrochemical etching is typically done in large volumes and thus the cost has been significantly reduced.
Methods of achieving a final device without the second high surface portion have included mechanical methods of polishing or lapping the material away. This is typically done in finished capacitors such as in U.S. Pat. No. 7,833,292 which is incorporated herein by reference. Mechanically removing the material is difficult to control when handling the finished components and may also damage the thin components.
The present invention provides a novel method of forming one sided foil in a way that takes advantage of commercially available foils. The present invention also provides an improved method for manufacturing capacitors using the one-sided foil.